A research team from the department of Chemical Engineering at the University of Soochow not far from Shanghai has come up with a hybrid solar panel which is able to generate electricity by harvesting the energy of falling rain. When raindrops strike the panel, their relatively weak impact activates a nanogenerator – i.e. a device designed to convert the mechanical energy produced from small-scale physical changes into electrical energy. The device produces friction between two transparent sheets made of different polymer materials. The electrostatic friction then generates tiny quantities of electricity. Multiplied by the number of raindrops which one single downpour might contain, sufficient electricity is produced to keep a solar panel working, even when the sky is cloudy and the level of sunlight rather low.This new technology, known as a triboelectric nanogenerator (TENG), is not entirely new. Researchers in the automobile industry began experimenting a couple of years ago with the 'triboelectric' effect to convert the friction of the vehicle's tires rubbing against the road so as to recharge electric engine batteries, but this is the first time the triboelectric approach has been successfully applied in the renewable energy sphere. This invention goes some way towards solving the fundamental problem that besets solar power: it is an 'intermittent' source of electricity that is only available when the sun is shining. So we might soon see the great promise of photovoltaic energy being fulfilled all over the world, even in areas where sunlight levels are rarely optimal.
By Arnaud Pagès